1. Field of the Invention
The present invention relates to an organic light emitting display, and a method for driving an organic light emitting display and a pixel circuit, and more particularly to an organic light emitting display, and a method for driving an organic light emitting display and a pixel circuit capable of improving a uniformity of a luminance.
2. Discussion of Related Art
Recently, various flat panel displays have been developed to substitute for cathode ray tube (CRT) displays because the CRT displays are relatively heavy and bulky. Flat panel displays include liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panel (PDP) displays, and organic light emitting displays.
Among the flat panel displays, the organic light emitting displays are self-emission devices that can emit light by recombination of electrons and holes. The organic light emitting display may be referred to as an organic electroluminescent display. The organic light emitting display has a high response speed that is more like the response speed of the CRT display than the response speed of the slower LCD that requires additional light source.
The organic light emitting display can be driven by a passive matrix method or an active matrix method. According to the passive matrix method, an anode and a cathode are formed to intersect (or cross-over) each other and a line is selected to be driven. According to the active matrix method, the amount of current that flows through an electroluminescent device (e.g., an organic light emitting diode (OLED)) is controlled by an active device. A thin film transistor (hereinafter, referred to as TFT) is mainly used as the active device. While the active matrix method is more complicated than the passive matrix method, it has advantages in that the amount of power consumption is small and that emission time is long.
However, when threshold voltages of TFTs are not uniform, the active matrix type organic light emitting display may not have uniform screen luminance. In particular, when an organic light emitting diode (OLED) continuously emits light during one frame, an influence due to an error of the threshold voltage is accumulated, thus further deteriorating the non-uniformity of the screen luminance.